1. Field of the Invention
The present invention relates to a sonic wave output device, a voice communication device, a sonic wave output method and a program.
2. Description of the Related Art
Various techniques for outputting sonic waves with directionality toward a listener of sound have been developed. For example, according to the technique disclosed in Japanese Unexamined Patent Application Publication No. S58-119293, ultrasonic waves generated by amplitude modulation of a sound signals are emitted to the air in order to obtain audible sound by a nonlinear parametric function. According to the technique disclosed in Japanese Unexamined Patent Application Publication No. H11-145915 or 2004-147311, ultrasonic waves generated by amplitude modulation of a sound signal are output from one of two speakers, and non-modulated ultrasonic waves are output from the other speaker, thereby generating a beat and providing a user with sound by the secondary component of the beat.
Further, Japanese Unexamined Patent Application Publication No. H7-87590 discloses a technique of detecting a user's location with use of an imaging device, a sensor or the like and optimizing directionality of sonic waves in the audible range.